"The animals were trying to tell us something. If only we knew that, not so many people would have died," said Fu Wenran, a retired farmer whose wife was among the estimated 240,000 who perished in Tangshan's quake on July 28, 1976.

Several survivors of the disaster in this northern city -- still the deadliest earthquake of modern times -- said the toll in this month's quake in southwestern China could have been minimised if such clues had been validated.

Chinese media reports and Internet blogs have buzzed with reports of mass migrations of thousands of frogs and toads near the quake region in Sichuan province just before the May 12 disaster, which left more than 80,000 people dead or missing.

Whether linked to the quake or not, there is little dispute among scientists that animals can predict earthquakes, possibly through sensitivity to pressure waves.

"Physical and chemical stimuli emanate from the earth prior to an earthquake and animals probably sense that," said Dr. George Pararas-Carayannis, a chemist and oceanographer who is president of the Honolulu-based Tsunami Society.

"Eventually, studies of animal behaviour could lead to better and more sophisticated sensors for use in short-term prediction."

Scientists can detect heightened earthquake risks by monitoring build-ups of seismological pressure, ground tilting and magnetic field changes, although no quake has ever been accurately predicted this way, he said.

Yet there are many other strange precursors whose utility in forecasting remains unexplored, said Pararas-Carayannis.

The 1976 Tangshan quake was a tour de force of such clues, survivors say.

Fu, then a farmer on the city's outskirts, said dogs erupted in wild howling and barking hours before the quake struck at 3:42 am.

Mice and snakes skittered around crazily in the open. Horses and cows kicked at their stable walls.

Water levels in local wells plunged in the weeks before, only to rise sharply in the hours preceding the quake, with many overflowing, he said.

Even Tangshan's people behaved strangely, he said.

"People were irritable and confused. There were many fights that night," said Fu, now 66.

At the time, the bad tempers were blamed on a sudden heat wave, strangely unforeseen by weather forecasts, said Chang Qing, 71, then a local photographer.

"It was extremely hot. At 2:00 am, people threw water on themselves and fanned themselves. But you know what? After the quake, it was suddenly much cooler," he said.

Similar temperature rises have been reported in other quakes around the world, with some scientists suspecting geothermal forces.

The same goes for mysterious brilliant lights seen in skies before large earthquakes since ancient times.

"It looked like explosions. Bright sudden flashes. But there was no sound," said Jiang Mo, 59, who recalls seeing them while lying awake in the pre-dawn heat.

"Many people saw them but nobody had an explanation."

Dubbed "earthquake lights", some scientists believe they may be the products of a traumatised mind, while geologists suggest a link to electromagnetic forces from deep underground.

Yet animal behaviour is widely believed to hold the most promise in forecasting.

China set up a group, now-disbanded, to study the issue in the 1960s. It was widely credited with accurately predicting a 7.3-magnitude 1975 quake in the northeastern Liaoning province.

But unless vastly more research is done, such oddities will remain more a source of wonder than part of a practical and accurate forecasting method, said retired biologist Huang Zhujian, former head of the team.

"We know animals can see an earthquake coming, but that can play only a supplemental role. We must depend principally on geological methods, and even those cannot clearly predict earthquakes," he said.

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